@TrollDecker said:

Giving myself a headache here, because my Terrahawks Blu-ray has arranged everything by production order, but TMDB has the episodes listed in what I assume is an original airing order in some country, that also contradicts the original UK airings on Wikipedia and the airdates listed on IMDb.

What are the TMDB dates based on, and what should they have been based on?

Here are the episode rules from the 'contribution bible':

https://www.themoviedb.org/bible/tv/59f743289251416e71000037

Here is the episode order from Anderson's website (but they aren't broken down by season):

https://www.gerryanderson.com/portfolio/terrahawks/